Oscillating hydraulic actuator and circuit therefor



Dec. 26, 1967 H. M. PURCELL I 3,359,370

' I OSCILLATING HYDRAULIC ACTUATQR AND CIRCUIT THEREFOR Filed Sept 2, 1965 v 2 Sheets-Sheet 1 /6 tab INVENTOR. HOWARD M. PURCELL Dec. 26, 1967 I ELL, 3,359,870

OSCILLAI'ING HYDRAULIC ACTUATOR AND CIRCUIT THEREFOR Filed Sept. 2, 1965 A 2 Sheets-Sheet 2 FIG-2 3e.

0 .1!! m2 2 FIG-7 64 FIG-5 INVENTOR.

HOWARD M. PURCELL MA-M United States Patent poration of Ohio Filed Sept. 2, 1965, Ser. No. 484,649 8 Claims. (Cl. 92121) This invention relates to hydraulic motors or actuators, particularly paddle type motors or actuators and to uses thereof and to circuitry involving such motors or actuators.

There are many instances in which hydraulic motors are employed for imparting a relatively short stroke to a work member, including imparting oscillatory movements to work members Within predetermined limits.

Usually reciprocable hydraulic motors consisting of cylinde'rs and pistons therein are employed for this service, but motors of this nature are relatively expensive and tend to leak at the rod end thereof and, furthermore, when employed for oscillating members work through a moment arm which varies and is many times shortest when the motor is required to develop the greatest power.

A particular instance where reciprocable hydraulic motors are employed and operated under the disadvantageous conditions as outlined above, is in connection with the operation of the tops of convertible automobiles. When reciprocable motors are employed for actuating the tops between their collapsible and raised positions, the moment arm through which the motor works is shortest at opposite ends of travel of the top and at which time the maximum developed power is required.

Such automobile tops require a motor at each side and the possibility arises that one of the motors will leak or will permit some slippage past the piston which will permit the motors to get out of step, whereupon the top being actuated will be twisted. Furthermore, one side of the top might stick and the other side will then travel ahead and the top structure will twist. It has been proposed to connect motors of this nature in series so that the displacement tfrom one will acutate the other and, in this manner, the motor will be completely in step but this requires that two motors of different sizes be manufactured and used on each convertible automobile. Parallel connected reciprocating motors as now employed are particularly disadvantageous when the top sticks on one side because the other side will proceed at twice the former speed and the top structure will twist very quickly.

The present invention is particularly concerned with the provision of an improved hydraulic motor having many possible uses, but particularly adapted for us'e for actuating automobile convertible tops.

An object of this invention is the provision of a paddle type hydraulic motor which is extremely inexpensive to manufacture.

Another object is the provision of a paddle type hydraulic motor which is substantially free of influence due to leakage.

Still another object of the present invention is the provision of a novel hydraulic motor particularly adapted for actuating the tops of convertible type automobiles.

Still another object of the present invention is the provision of an improved actuator for actuating the convertible top of an automobile and having an improved mounting means for the actuator which is conserving of space within the automobile structure.

Another object of this invention is the provision of an improved hydraulic actuator for a convertible automobile top having a novel means of making fluid connection thereto.

Still another object of this invention is the provision of a paddle type hydraulic actuator having the side walls stiffened in such a manner that the actuator can be made substantially any size and operate under substantially any pressure without deflection of the side walls of the actuator.

It is .also an object of this invention to provide a paddle type hydraulic actuator which is substantially self-bleeding in the event air gets into the hydraulic system and which does not require the provision of auxiliary stops and the like to control the movements of the paddle of the actuator.

Still another object of this invention is the provision of an improved seal arrangement for the paddle of a paddle type hydraulic actuator in which the mounting of the seals on the paddle is quite simple and wherein the seals themselves can be simply constructed while at the same time highly effective sealing of the unit is had.

These and other objects and advantages of the present invention will become more apparent upon reference to the following specification taken in connection with the accompanying drawings, in which:

FIGURE 1 is a schematic view showing how two paddle type actuators according to the present invention are connected in series in a hydraulic circuit for actuating the convertible top of an automobile or a similar structure.

FIGURE 2 is an elevational view of the motor or actuator of the present invention, partly broken away, to show the internal structure and also illustrating a mounting plate forming a part of the present invention.

FIGURE 3 is a view taken substantially on line III- III on FIGURE 2 partly in section and partly in elevation showing details of construction of the actuator.

FIGURE 4 is a sectional view indicated by line IV- IV on FIGURE 2 showing a stroke limiting check valve arrangement forming a part of the present invention.

FIGURE 5 is a transverse section indicated on line V-V of FIGURE 2 showing details of construction in connection with the connection of the paddle of the actuator to its shaft.

FIGURE 6 is an exploded perspective view showing details of construction in connection with the paddle structure. 7

FIGURE 7 is a somewhat diagrammatic view drawn at increased scale showing how conduits are introduced into the casing of the actuator for being welded in place therein.

FIGURE 8 is a fragmentary sectional view showing a manner of connecting flexible conduits to the rigid conduits leading into the actuator.

FIGURE 9 is a somewhat schematic perspective view showing an actuator according to the present invention mounted in a vehicle body.

Referring to the drawings somewhat more in detail, in FIGURE 1, 10 indicates the actuating arms of a conventional convertible automobile top. Each arm has connected thereto a hydraulic actuator generally indicated at 12. These actuators are identical as to volumetric capacity and are advantageously connected in a series circuit so that the fluid expelled by the leading motor in the circuit will serve to actuate the trailing motor in the circuit. In the circuit illustrated there is a pump 14 delivering continuously in one direction into a conduit 16. Conduit 16 leads to the inlet of a reversing valve 18, which may be a closed center or an open center valve, depending upon the nature of the service of pump 14. Valve 18 has leading therefrom a first service conduit 20 leading to one side of one of the hydraulic actuators 12 and a second service line 22 leading to the opposite side of the other of the hydraulic actuators. The two adjacent sides of the actuators are connected by conduit 24 so that a series circuit is obtained.

A lever or shift knob or the like at 26 will serve for shifting valve 18 so as to cause driving of actuators 12 in one direction or the other and this lever may have a neutral position of adjustment when the top is either completely up or completely down or alternatively, the drive motor for pump 14 may be deenergized at this time. Since the actuators have the same volumetric capacity it will be apparent that the members actuated thereby will move in unison at all times. The top structure thus will not twist and, in the event one side of the top becomes stuck for any reason, the other side will not run ahead. The actuation of the top by the actuators is thus much more reliable than can be had with reciprocating motors and there is substantially no chance for the top structure to become twisted because of faulty operation of the hydraulic actuators according to the present invention.

Turning now to FIGURES 2 and 3, it will be seen that the actuator comprises two identically shaped casing parts 28 and 30 which are placed in edge to edge engagement and welded together at 32. By forming the casing parts to identical shapes, the cost of the actuator is reduced and by placing the casing parts together in edge to edge relation and welding them together connecting screws or bolts and sealing gaskets and the like are eliminated from the structure. This, of course, makes for a very economical actuator structure which is inexpensive enough that it can be constructed, as shown, as a sealed unit and be replaced in its entirety if, for any reason, it becomes faulty in operation.

As will be appreciated in FIGURE 2, the flat side walls of the actuator may be relatively extensive and if the actuator is operated at high pressure the possibility exists that these flat walls will deflect somewhat and permit leakage at the actuator. This ordinarily is. not a serious consideration but, in any event, it is completely prevented by the arrangement of the present invention by mounting on opposite sides of the actuator the plates 34 and 36, best seen in FIGURE 3. These plates are spot welded at a plurality of points to the pertaining side wall of the actuator and comprise an embossed region 38 extending over that portion of the pertaining side wall that is most likely to yield under high pressure within the actuator. I have found that the provision of these simple inexpensive stiffening plates on the outside of the actuator prevents deflection of the side walls and adapts the actuators for operation under relatively high pressure.

Advantageously, side wall 36 extends beyond the limits of the actuator and is provided with apertures 40 therein for receiving mounting bolts so that the actuator can be mounted by availing of plate 36. This also makes for a compact economical structure. Still further, it will be evident that the output shaft of the actuator, indicated by reference numeral 42, extends out of the actuator on the side thereof adjacent plate 36 and extends through the said plate and carries the member 44 which is connected to the part 10 operated by the actuator. Because of this arrangement of the actuator parts, it is possible, in an automobile structure, to form a hole in a mounting panel and insert the actuator structure into the hole and support the actuator in place 'by bolts extending through holes 40 in plate 36.

The entire actuator structure can thus be positioned close inside the outside wall of the car and in this manner a substantial saving of space is realized, up to six inches on each side of the vehicle.

FIGURE 9 shows somewhat schematically in perspective how this is achieved and in this figure reference numeral 46 indicates the outside of the body and reference numeral 48 indicates the inside panel and which is apertured for receiving the actuator 12 and which actuator is supported thereon by bolts 50 extending through the bolt holes in stiffening plate 36. In the usual convertible top arrangement, about six inches more at each side of the car at the back seat is required for receiving the reciprocating hydraulic motors according to the prior art. Referring again to FIGURES 2 and 3,

4 shaft means 52 extends transversely through the actuator casing near the apex thereof and carries a paddle generally indicated at 54.

As will be seen in FIGURES 2, 3 and 6, the paddle 54 comprises a central plate 56 and plates 58 at opposite sides thereof, each said plate having a recessed center portion 60 on which is provided projections so that the plates 58 can be welded to opposite sides of plates 56. It will be evident that, because of the raised portions 60 in plates 58, when they are welded to opposite sides of plate 56 a space is left around the periphery of the paddle. These spaces are availed of for receiving the sealing members 62 which are of a rubber like material, preferably a synthetic rubber, and which provide two spaced regions of sealing engagement of the paddle with the walls of the casing.

It will be seen that the plates 58 also comprise the regions 64 which provide clearance around the shaft means 52 and around which regions the seal members 62 extend so that the entire periphery of the paddle including the regions thereof passing about shaft 52 have sealing engagement with the casing. FIGURE 6 will also show that central plate 56 has an aperture 66 therein and that plates 58 are provided with apertures 68 which register with aperture 66 and, furthermore, that seal members 62 have apertures 70 which register with the aperture 66 in plate 56.

This aperture is availed of for receiving a double ended check valve 72 which has heads thereon on opposite sides of central plates 56 and beneath which heads are disposed the resilient annular 0 rings 74.

The check valve member 72 has stem portions 76 projecting in opposite directions therefrom which are availed of for supporting the compression springs 78. The double ended check valve is provided so that if one motor reaches the end of its travel before the other, fluid will be bypassed through the said one motor thereby permitting continued movement of the other motor until it reaches the end of its travel.

However, upon reversing of the direction of fluid supplied to the actuators or motors, the check valves for the actuators or motors will close to the fluid and full pressure will stand upon the upstream side of the respective paddles. It will be evident that fluid pressure in FIG- URE 2 passing from the underside of the paddle through the aperture in plate 56- will engage the inside of the upper O ring 74 and cause expansion thereof so that the fluid can pass through the aperture.

However, upon fluid pressure being delivered to the upper side of the paddle in FIGURE 2, the pertaining O ring will be pressed inwardly into the wedge shaped region between the upper head of the check valve member and plate 56 and tightly sealed against fluid flow through aperture 66.

As to shaft means 52, as will be seen in FIGURE 5, this comprises a first shaft section 52a and a second shaft section 52b each said section being provided with a slot as at 80 for receiving the necked down region 82 of plate 56. The shafts are also provided with flats at 84 and these flats are adapted for engagement by the correspondingly flattened regions 86 of the outer plate members 58. When the several parts of the paddle are assembled and held in a fixture, welding of the upstanding regions of plate 58 to central plate 56 and welding of the flattened regions 86 of plate 58 to the shaft portions 52a and 52b will result in an extremely strong rigid paddle structure but at a minimum of expense and with all the parts thereof rigidly held in alignment with each other.

As will be seen in FIGURES 3 and 5, the side walls of the casing of the actuator may be formed inwardly as at 90 in a sort of conical configuration and thereafter, when the plates 34 and 36 are mounted in place a conical recess will be formed surrounding the shaft means 52. This conical recess is availed of for receiving a sealing O ring 92 at each end of shaft means 52 whereby the shaft means is tightly sealed to the casing in addition to the seals provided by the two aforementioned seals 62. The paddle type actuator structure of the present invention is thus extremely eflicient with respect to containing liquid and substantially no leakage therefrom is encountered in the normal course of events.

The connecting of fluid lines to the actuator is accomplished in a novel manner according to the present invention. As will be seen in FIGURES 2 and 8, the casing is pierced as at 94 on opposite sides of the apex thereof. The piercing of the casing can take place in one of the sections 28 or 30 or each can be pierced at the same place. In either case, there is a fluid port in the casing on each side of the apex thereof. As will be seen in FIGURE 7, this piercing is done from the outside of the casing inwardly so that a fairly sharp rim part 96 is provided. This sharp rim part is availed of for eiTect-ing projection welding of rigid conduits to the casing. The rigid conduit is shown at 98 in FIGURE 7 with the same numbers being applied to the conduits in FIGURE 2 and it will be seen to be flared at 100 inside the actuator casing.

The aperture 94 is of such a size that the rigid conduit can be flared and then fed through hole 94 from the inside of the casing until the flare 100 is disposed adjacent the sharp edge about the periphery. A welding tool 102 can then be availed of to engage the end of the rigid conduit 98 and press the flared end 100 thereof against sharp rim 96 at which time a suitable welding current will weld the flared part to the sharp rim part 96 and effect a rigid fluid tight connection of the conduit to the casing.

This manner of connecting the fluid conduit to the casing is at one time rapid and inexpensive and provides an excellent fluid connection Without the necessity of employing threaded or riveted connections which are accessible only with difiiculty. For the reason that the conduits 98 are rigid with the actuator and extend downwardly over the mounting plate portion 36 as will be seen in FIGURE 2, fluid connection can easily be made to the rigid conduits after the actuator has been placed in position in an automobile body. It is not always the case that fluid connections can be made in this simple easy manner.

FIGURE 8 shows a manner in which connections can easily be made. In FIGURE 8 a threaded member 104 is slipped over conduit 98 and it has a recess for receiving the end of flexible tube 106. Mounted over tube 106 is a deformable ferrule 108 and this ferrule is adapted for being compressingly engaged between member 104 and the inside of a nut 110 threaded on member 104. A connection of this nature can easily be made and when nut 110 is drawn up tight, ferrule 108 will pressure flexible tube 106 into sealing engagement with rigid conduit 98 and leakage at this point in the hydraulic system will thereby be prevented.

T-he paddle type actuator of the present invention has been particularly described as being useful for the actuation of automobile convertible tops but it will be apparent that it is a compact, highly effieient unit and can be also be employed for actuating other devices, such as doors, windows and the like as well as conventi ble automobile tops. Where the motor is used in multiples, as in connection with automolbile convertible top, it offers a particular advantage in that it can be connected in series with other motors and all thereof will take exactly the same stroker or if, due to leakage in one of the motors or actuators, it will come to a halt at the end of its travel and hydraulic fluid will by-pass there through until the other motors catch up.

As will be seen in FIGURE 2, the end walls of the casing may be formed inwardly as at 112 to provide points of albutment of these walls with the paddle of the actuator in its extreme positions whereby no auxiliary stops or the like are required. It will also be appaent that the points of connection of the conduit 98 with the easing of the actuator are so lo'c-ate'd that the actuator tends to be self-bleeding and air introduced for any reason into the hydraulic system will gradually be expelled from the actuators through the conduits 98.

As to the hydraulic circuit of FIGURE 1, a unidirectional delivery pump is shown at 14 but it would also be possible to employ a reversible pump as indicated at 114 and to drive this reversible pump by reversible motor 116 in which case no valving at all would be required for Obtaining reversible operation of the actuators.

Merely energization and deenergization of motor 116 would start and stop the actuators and the direction of rotation of motor 116 would determine the direction of movement of the actuators.

It will also be apparent at this point that as much fluid is expelled from the actuators as is introduced therein and for this reason there is no change in the hydraulic volume of a reservoir from which the actuator draws fluid and there is no change in the volume of the total fluid in any system containing a pump which is connected for supplying fluid under pressure to the actuator. For this reason it becomes possible, when utilizing the actuators of the present invention in an automobile for actuating the top or the windows or for other purposes, to draw fluid for the actuators from the power steering pump or any other actuating pump that is provided in the system which has sufficient pressure and capacity for driving the actuators. There will be no change in the fluid volume of such a system and thereby no dangerous conditions would arise.

Due to the simplicity of making fluid connections to the actuators according to the present invention is is readily possible to connect the actuators in the power steering system of an automobile which would provide for driving of the actuators at any time that the automobile engine was running. Operation of the actuators at any time is, of course, possible when the pump therefor is independent and is operated by its own electric motor.

A feature of the present invention is to be seen in the arrangement of valve 18 in FIGURE 1, wherein the valve spool is centered by springs 18a and 18b so that whenever lever or knob 26 is released the valve member will center and in this position a bypass is afforded between conduits 20 and 22 by the bore 18c in the valve member. This arrangement permits the top to be raised and lowered manually because fluid will freely bypass fron one actuator to the other when valve 18 is in a neutral position. The necessity for manual operation of the top might arise in connection with failure of the pressure source for the actuators either through failure of the drive motor for the actuator pump when the pump is individual to the actuators, or when the automobile engine is halted if the pressure source is the power steering pump. Knob or lever 26 may advantageously be mounted on the dash panel of an automobile for convenient operation.

As mentioned before, the use ofthe actuator according to the present invention wherein no differential areas exist permits the fluid source to be the power steering pump of the vehicle in which the actuators are mounted because the volume of fluid in the system will not change because of operation of the actuators.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. A hydraulic actuator comprising; a casing substantially sector shaped in longitudinal cross section and rectangular shaped in transverse cross section, a shaft extending into the casing substantially at the apex of said sector, a paddle in the casing sealingly fitted in the casing and fixed to said shaft, and means in said casing near said apex for selectively admitting pressure fluid into or exhausting fluid from said casing on respectively opposite side of said paddle to rotate said shaft, said casing comprising two substantially identical sector shaped portions having marginal flanges upstanding at the periphery thereof, said portions being placed together with the respective flanges coplanar and in engagement, and weld means sealingly rigidly connecting said flanges together, said paddle having a pair of grooves therein extending completly around the edge of the paddle and including portions extending around opposite sides of the shaft, and resilient seal means in said groove means to seal the paddle to the casing and including the region thereof around said shaft.

2. A hydraulic actuator comprising; a casing substan tially sector shaped in longitudinal cross section and rectangular shaped in transverse cross section, a shaft extending into the casing substantially at the apex of said sector, a paddle in the casing sealingly fitted in the casing and fixed to said shaft, means in the casing near said apex for selectively admitting pressure fluid into or exhausting fluid from said casing on respectively opposite sides of said paddle to rotate said shaft, said casing comprising two substantially identical sector shaped portions, having axial marginal flanges upstanding at the periphery thereof, said portions being placed together with the respective flanges coplanar and in edge to edge engagement, weld means sealingly rigidly connecting said flanges together, said paddle having a pair of grooves extending completely around the edge of the paddle and including portions extending around opposite sides of the shaft, and a pair of resilient seal elements disposed in the respective grooves to seal the paddle to the casing and including the region thereof around said shaft.

3. A hydraulic actuator comprising; a casing substantially sector shaped in longitudinal cross section and rectangular shaped in transverse cross section, a shaft extending into the casing substantially at the apex of said sector, a paddle in the casing sealingly fitted in the casing and fixed to said shaft, means in said casing near said apex for selectively admitting pressure fluid into or exhausting fluid from said casing on respectively opposite sides of said paddle to rotate said shaft, said casing comprising two substantially identical sector shaped portions, having axial marginal flanges upstanding at the periphery thereof, said portions being placed together with the respective flanges coplanar and in edge to edge engagement, weld means sealingly rigidly connecting said flanges together, said paddle having a pair of grooves extending completely around the edge of the paddle and including portions extending around opposite sides of the shaft, a pair of resilient seals in said grooves to seal the paddle to the casing and including the region thereof around said shaft, said paddle comprising two substantially identical members of uniform thickness and formed so as to have marginal steps thereon arranged in face to face relation and a flat plate therebetween so that the said steps and plate cooperate to form said grooves, and weld means fixedly securing said members and plate together and to said shaft.

4. A hydraulic actuator comprising; a casing substantially sector shaped in longitudinal cross section and rectangular shaped in transverse cross section, a shaft extending into the casing substantially at the apex of said sector, a paddle in the casing sealingly fitted in the casing and fixed to said shaft, means for selectively admitting pressure fluid into or exhausting fluid from said casing on respectively opposite sides of said paddle to rotate said shaft, a hole through the paddle, a check valve member comprising a shank portion extending slidably through said hole and with clearance in the hole to permit fluid flow therethrough, a tapered head on each end of the shank larger than said hole, resilient O-ring means between and engaging each head and the adjacent face of the paddle and adapted for sealing between each head and the paddle when the respective heads are subjected to fluid pressure, said shank being of such length as to permit a small amount of axial movement ofsaid check valve member relative to the paddle, a stem on each end of the shank, and a spring on each stem projecting therefrom for engagement with an end wall of the actuator.

5. A hydraulic actuator comprising; a casing substantially sector shaped in longitudinal cross section and rectangular shaped in transverse cross section, a shaft extending into the casing substantially at the apex of said sector, a paddle in the casing sealingly fitted in the casing and fixed to said shaft, means for selectively admitting pressure fluid into or exhausting fluid from said casing 0n respectively opposite sides of said paddle to rotate said shaft, a hole through the paddle, a check valve member comprising a shank portion extending slidably through said hole and with clearance in the hole to permit fluid flow therethrough and a head on each end of the shank larger than said hole, and resilient O-ring means between and engaging each head and the adjacent face of the paddle and adapted for sealing between each head and the paddle when the respective heads are subjected to fluid pressure, said shank being of such length as to permit a small amount of axial movement of the check valve member relative to the paddle, each said head tapering inwardly on the side toward the paddle, a stem on each end of the shank, and a spring on each stern projecting therefrom for engagement with an end wall of the actuator.

6. In a paddle type hydraulic actuator; a substantially sector shaped casing having a flat side walls, apertures in said side walls near the apex of the casing, a paddle in the casing sealingly engaging the inside thereof, shaft means fixed to the paddle and extending out of the casing through said apertures, said paddle comprising a central flat plate and outer plates welded to opposite faces thereof and defining peripheral groove means for receiving sealing means to seal the paddle to the inside of the casing, said shaft means comprising a shaft section projecting from each side of said paddle, the adjacent inner ends of said shaft sections being slotted and receiving said central plate in the slots, and welding connecting said outer plates to said shaft sections, said central plate having a necked down region for receiving the ends of said shaft sections so the said sections will have substantial overlap with said outer plates, said shaft sections having flats thereon where overlapped by said outer plates, and said outer plates having flats thereon engaging the flats on said shaft sections, said interengaging flats forming the region wherein the outer plates are welded to the shaft sections.

7. In a paddle type hydraulic actuator; a substantially sector shaped casing having flat side walls, apertures in said side walls near the apex of the casing, a paddle in the casing sealingly engaging the inside thereof, shaft means fixed to the paddle and extending out of the casing through said aperture, said casing having a hole pierced therein on each side of the apex from the outside of the casing to the inside thereof so as to form a rim about the periphery of each hole on the inside of the casing, a rigid conduit extending through each hole and flared inside the casing, and welding joining the flared end of each conduit to the said rim of its pertaining hole.

8. In a paddle type hydraulic actuator; a substantially sector shaped casing having flat side walls, apertures in said side walls near the apex of the casing, a paddle in the casing sealingly engaging the inside thereof, shaft rneans fixed to the paddle and extending out of the casing through said apertures, said paddle comprising a central flat plate and outer plates welded to opposite faces thereof and defining peripheral groove means for receiving sealing means to seal the paddle to the inside of the casing, said sealing means comprising a sealing member on each side of said central plate, each sealing member comprising a flat portion for insertion into the groove means on the pertaining side of the central plate and an angular lip portion extending about the entire periphery of the respective sealing member and the paddle, said central plate extending to near the inside surface of said casing and said outer plates terminating in spaced relation to the inside surface of the casing and fitting inside the lip portion of the pertaining sealing member.

References Cited UNITED STATES PATENTS 5 8/1935 Horton et a1. 92-125 X 6/ 1936 Horton et a1 92-67 X 11/1941 Neubert 91-401 X 2/ 1949 Raybould 285-249 6/1950 Floraday 92-120 X 10 Horton 296-117 OShei 92-125 Orr 296-117 Greer 296-117 X Tyler 60-52 MacMillin 60-52 Giampapa et a1 60-52 X McLeod 296-117 X Wilkinson 60-52 X Neilan 91-401 EDGAR W. GEOGHEGAN, Primary Examiner. 

1. A HYDRAULIC ACTUATOR COMPRISING: A CASING SUBSTANTIALLY SECTOR SHAPED IN LONGITUDINAL CROSS SECTION AND RECTANGULAR SHAPED IN TRANSVERSE CROSS SECTION, A SHAFT EXTENDING INTO THE CASING SUBSTANTIALLY AT THE APEX OF SAID SECTOR, A PADDLE IN THE CASING SEALINGLY FITTED IN THE CASING AND FIXED TO SAID SHAFT, AND MEANS IN SAID CASING NEAR SAID APEX FOR SELECTIVELY ADMITTING PRESSURE FLUID INTO OR EXHAUSTING FLUID FROM SAID CASING ON RESPECTIVELY OPPOSITE SIDE OF SAID PADDLE TO ROTATE SAID SHAFT, SAID CASING COMPRISING TWO SUBSTANTIALLY IDENTICAL SECTOR SHAPED PORTIONS HAVING MARGINAL FLANGES UPSTANDING AT THE PERIPHERY THEREOF, SAID PORTIONS BEING PLACED TOGETHER WITH THE RESPECTIVE FLANGES COPLANAR AND IN ENGAGEMENT, AND WELD MEANS SEALINGLY RIGIDLY CONNECTING SAID FLANGES TOGETHER, SAID PADDLE HAVING A PAIR OF GROOVES THEREIN EXTENDING COMPLETELY AROUND THE EDGE OF THE PADDLE AND INCLUDING PORTIONS EXTENDING AROUND OPPOSITE SIDES OF THE SHAFT, AND RESILIENT SEAL MEANS IN SAID GROOVE MEANS TO SEAL THE PADDLE TO THE CASING AND INCLUDING THE REGION THEREOF AROUND SAID SHAFT. 